Carburetor accelerating pump



Oct. 27, 1942.

A. TRlsLER 2,299,863

CARBURETOR ACCELERATING PUMP Filed June 17, 1940 wat Gttorneg Patented ocazv, 1942 cAanUaa'ron 2,299,863 AccELEaA'rlNG PUMP Milton Trisier, Birmingham, Mich., assigner to General Motors Corporation, Detroit, Mich., a

corporation of Delaware Application June 17, 1940, Serial No. 340,878 1 Claim. (Cl. mil-34) This invention relates to means associated with a carburetor of the internal combustion engine type forproviding temporary enrichment of the charge upon sudden increase in the demand for explosivemixture. In modern carburetor prac- It is common practice to connect the so-called A accelerating pump to the throttle valve actuating means in such manner that the pump delivers to the mixing chambera denite or predetermined quantity of liquid for each opening movement of the throttle through a given range. It has been found/however, that the discharge from the pump should be graduated somewhat in accordance with the rapidity of opening movement of the throttle and particularly that, if the liquid forcing device is actuated to the same extent by a very abrupt opening of the throttle as it is by a slower throttle opening. the delivery of fuel upon the more abrupt movement is unnecessarily and detrirnentally excessive.

'I'he primary object of my invention therefore is to provide an accelerating device in which the delivery of the accelerating charge is graduated in accordance with the rate of opening movement of the throttle valve, less fuel being discharged when the throttle is suddenly opened than when the opening movement is slower. Further objects and advantages will appear from the following description taken in connection with the accompanying drawing in which Figure 1 is an elevation of a carburetor showing means for actuating a fuel discharge device from the throttle valve, and

float bowl is indicated at and a conventional float at I2 whereby liquid f uel is maintained in the bowl vor reservoir at a predetermined level as indicated at I3.

Associated with the reservoir Il is an auxiliary fuel chamber I4 to which fuel may be conducted from the reservoir Il through passage I5. A check valve I6 permits flow to the auxiliary chamber but prevents flow in the opposite direction. 'I'he auxiliary chamber is connected through outlet Il, check valve I8, and passage I3 to tne "accelerating jet" 20 through which liquid fuel forced out of chamber I4 is discharged into the mixing chamber.

The chamber I4 has associated therewith a piston or plunger 2| operative upon outward movement to increase, and upon inward movement to decrease the volume of the chamber. This plunger may be sealed' by the usual packing 22 of flexible material expanded by a spring ring 23 and retained by a perforated cap 24. The plunger is provided with an internal passage 25 having a valve seat 28 and communicating through the aperture 21 with the interior of the reservoir |l. A valve 28 held upon the seat 25 by spring 29 servesinormally to close the passage 25 during inward movement of the plunger. Normally, therefore, when the plunger is moved out-l wardly liquid will be drawn into the chamber I4 from the reservoir |I and when the plunger is moved inwardly liquid contained therein will be discharged through the jet 20.

To effect movement of the plunger, I have shown a U-shaped rod 30 one end of which is connected by link 3| to an arm 32 on the throttle Figure 2 is a sectional elevation showing in de..

tail a fuel discharge device embodying the present invention. y

Referring to the drawing, 5 indicates a carburetor body which may be of any equal or suitable form including a mixing chamber 8, one or more venturis l, 8, and means for delivering fuel thereto, such as a jet 9 from which fuel is discharged by reason of the suction exerted at the jet opening. A throttle valve I0 serves in the usual manner to control the flow of mixture from the mixing chamber to the engine, the carburetor shaft. The other end of the rod is slotted at 33 and is slidably i'ltted in the bore 34 of an extension 35 of plunger 2l. A pin 36 passing through slot 33 limits movement of rod 38 relative to plunger 2|. The valve 28 is provided with an extension 3l arranged in the path of movement of rod 30 in such manner that as the rod nears the inward limit of its movement relative to plunger 2| the end of the rod contacts the valve extension 3l and thereby opens thevalve. A portion of the liquid then under pressure contained in chamber I4 may thereupon escape through cap 24, passage 25, and aperture 2l to the reservoir I I, the quantity thus being bypassed being determined, of course, by the pressure upon the liquid and by the size of the passages and the extent of opening of the valve 28.

A spring 38 is arranged between the plunger 2| and a collar or abutment 39 xedly secured being illustrated as of the downdraft type. A to rod 30. This spring provides resilient connection betweenr the rod and the plunger, the strength oi the spring being so selected that. during opening movement of the throttleup to a certain predetermined rate, the plunger will be forced inwardly by the action oi the rod upon the spring and without permitting movement of the rod relatively to the plunger sumciently to actuate valve 28. When, however, this rate 0I move ment of the throttle is exceeded, the resistance to discharge v from chamber Il increases, the spring 38 is correspondingly stressed, and movement oi' rod 30 in bore 34 occurs suflicientlyto eect opening of valve 28 and thus permitting the bypassing oi' a portion of the liquid in chamber I4 back to the reservoir or other source of.

means as well as other changes in details of con- 25 struction may be utilized, depending upon the particular type and structure o! carburetor em- Dloyed.

I claim:

An accelerator pump for carburetor; comprising the combination with a carburetor having a throttle valve, a mixing chamber and a fuel reservoir of a pump chamber-whose intake communicates with said reservoir and whose outlet communicates with said mixing chamber. a plunger in said pump chamber having a bypass passage While the connection of 20 therein leading from said pump chamber to said reservoir, a valve carried by said plunger and controlling now through said passagefan actuator operable in response to movement of said throttle valve and connected to said plunger by means permitting limited relative movement between said parts and resilient means tending to restrain such movement as the plunger moves inwardly, an extension on said bypass valve termin'ating near the actuator whereby the bypass valve is actuated by contact between the actuator and the extension upon occurrence of such movement to a predetermined extent.

MILTON A. 'I'RISLER. 

